Typically, a transmission reliability of an uplink transmission from a communication device (UE) to a base station of a cellular network depends on a channel quality of the uplink channel. To increase the transmission reliability, it is possible to adapt various parameters of the uplink channel, e.g., properties of a multi-antenna transmission, time and/or frequency resources employed for the uplink transmission, etc. This is sometimes referred to as link adaptation.
To enable comparably accurate and effective link adaptation, it is typically required to assess the quality of the uplink channel. For this, a channel reference signal may be employed. The channel reference signal may be transmitted according to a transmission pattern, i.e., at pre-defined time positions and/or frequency positions. E.g., one such channel reference signal is the sounding reference signal (SRS) in as specified by the Third Generation Partnership Project (3GPP) Technical Specification (TS) 36.213, version 12.2.0 of June 2014, section 8.2.
Generally, transmitting the channel reference signal requires resources on the uplink channel. E.g., in case of the 3GPP Long Term Evolution (LTE) standard, a certain symbol of a subframe may be occupied by the channel reference signal. Therefore, while—in terms of accurate link adaptation—frequent transmission of the channel reference signal may be favoured, on the other hand the frequent transmission cause increased traffic on the uplink channel and may thereby lead to increasing interference, etc. Resources on the uplink channel are therefore occupied.